Margins of Safety: Avoiding Power-On Stalls

airplane pilots begin practicing stall recognition and recovery before their first solo flights then demonstrate those skills repeatedly on their check rides and flight reviews still every year unintended stalls are among the leading causes of fatal accidents why one major reason is that the stalls we practice in training don't look or feel much like those that catch pilots off-guard take the departure or power on stall aside from the unusually steep pitch attitude the way they're simulated during training is really pretty tranquil airplane computer for takeoff good now motor rotation disease I put smoothly add power and pitch the nose up and it had enough weight rudder there's the stall warning they're bring good very nice but unexpected stalls during takeoffs or go-arounds are something else entirely sudden sharp and frightening at low altitude even a brief loss of aircraft control may be unrecoverable ah what are the differences - really and the first is just that the pilot practicing stalls knows what's coming and is ready for it and because she knows what's happening and her instructor is coaching her she's paying attention to keeping her control input smooth and the airplane coordinated and since the airplanes coordinated the stall breaks pretty much straight ahead and recoveries just a matter of lowering the nose there might not be any loss of altitude at all while if the stalls not coordinated and one wing breaks first losses of both altitude and directional control are pretty well guaranteed oh and did we mention that we don't usually enter practice stalls with a lot of nose up trim while some nose up trim is great for an actual landing it may work against the pilot in the event of a go-around forward pressure may be needed on the controls in order to counteract the trim and keep from stalling the aerodynamics of power installs are the same in takeoffs and go arounds but the situations that trigger them are not the big problems and go arounds are surprised and hurry something unexpected happens and the pilot wants to get away from the runway now so rather than flying the airplane through a controlled transition smoothly adding power while holding the nose down to gain air speed then retracting flaps and re trimming he jams in too much throttle too quickly and maybe pulls when he should have pushed the result the airplane continues to seek it's trimmed airspeed and pitches up until it exceeds the critical angle of attack on one wing before the other if the pilots been slow to add enough rudder prematurely retracting flaps when the airplanes already on the verge of stalling only makes things worse the fix first of all always expect to go around and be ready for it practice it frequently enough to make it second nature remember that go arounds don't usually require an immediate climb the point is simply not to land so first build airspeed flying straight and level pay conscious attention to keeping the pitch attitude flat and adding enough rudder to keep the nose tracking straight until you've gained enough speed to climb make the necessary configuration changes one at a time and in the correct sequence as airspeed permits and maybe consider using no more nose up trim than necessary on final it makes a difference takeoff stalls are most often the result of pilots trying to force airplanes to fly before they're ready perhaps it's because of obstructions off the end of a short runway maybe the airplanes overweight or density altitude has sapped its performance or the flap settings wrong whatever the reason trying to pull the airplane off the ground by pure willpower kourt's a departure stall too high an angle of attack at to load and airspeed actually prevents you from climbing and reacting to that by pulling harder can pull you right over the edge here to the fix is simple though maybe not easy force yourself to remember a couple of simple facts no other airspeed will give you a steeper climb than holding VX none will gain altitude faster than v-y with a proper configuration set nailing your airspeed is the one thing that will give you the best chance of making it out of there with that in mind you should be motivated to do meaningful departure planning anytime the outcomes not certain if you can't get exact weights on passengers in cargo here on the side of caution and add a 50% margin to the booked distance for clearing a 50-foot obstacle that means that if the distance required is more than two-thirds of the distance available you'll need to find ways to shorten it consider reducing weight leave some cargo behind or have passengers meet you at an airport with a longer runway if that's not enough wait for cooler weather stronger headwinds or both and unless your airplanes turbocharged or turbine powered you'll need to remember to lean for best power at higher density altitudes finally choose an abort point and stick with it as a rule of thumb you should reach at least 70% of rotation speed by the time you've used half the runway shorter fields may require even more conservative rules to preserve enough room to stop if you haven't reached your target air speed by the time you pass the chosen landmark pull off the power and stop while you still can trying to take off without calculating performance requirements is a gamble you may not get to take twice and if the numbers aren't favorable it doesn't matter how badly you need to get there postponing until conditions improve will be less expensive and less traumatic then betting that things will go perfectly and losing corporate jet and airline pilots conduct a detailed departure briefing for every takeoff before the airplane ever begins to move they pin down exactly how they'll respond to anything unexpected at each stage of the attempt if that's good enough for the safest operators in the industry why should it be good enough for us stall avoidance isn't difficult but it does take awareness of the airplanes limitations and what it's doing in space at low altitudes even perfect recovery technique may not keep your nose off the ground so the best option is prevention that starts with recognition of the circumstances that lead to unexpected stalls angle-of-attack indicators can be a big help but since most of the fleet doesn't have them yet and won't for some time the first line of defense is still when it's been for a century alertness understanding discipline and plenty of practice of the essential elements of airmanship

Channel: Air Safety Institute

Views: 219,298

Rating: 4.9368677 out of 5

Keywords: Aircraft Owners And Pilots Association (Membership Organization), Aviation Safety (Literature Subject), Fixed-wing Aircraft (Industry), Aviation (Industry), Aerodynamics (Field Of Study), Flight Training (Literature Subject), Stall

Id: EnvtwqsnVKI

Length: 8min 14sec (494 seconds)

Published: Mon Nov 16 2015